1. Field of the Invention
The field of the invention relates to pulley systems with the view to overcoming conditions particularly encountered in such as power transmission and indexing metal belt systems.
2. Description of the Prior Art
U.S. Pat. No. 3,467,450 to Schmidt et al shows an eccentrically adjustable roller. Bushing 30 is eccentric. This eccentricity is constant over the width of the bushing and herein lies the difference over the present invention. In a standard two pulley metal belt system, the teaching would only change the tension in the system due to the constant eccentricity. Contrariwise, in the present invention, it will become apparent that a skew angle provides for the pivotal action so necessary in order to allow for tracking adjustment.
U.S. Pat. No. 2,279,887 to Hathorn shows an adjustable mounting for rotational members. There the teaching is of a pulley/bearing assembly which is allowed to pivot between a set of spherical washers. Accordingly, the necessary tracking characteristics are met in a standard two pulley system. This patent achieves the principles as will be seen in the approach taught in the present invention, but, and this is significant, through a different means. As will appear, the system of this invention varies with reference to the mounting of multiple pulleys on a common shaft. In the reference patent, the adjustments depend on the loosening of a bolt and nut assembly (10 and 16) so that all of the pulleys float freely. As will appear herefollowing, the teaching of the present invention allows each pulley to be adjusted independently of each other and this is accomplished simply by rotating the bushing about the stationary shaft.
U.S. Pat. No. 3,064,487 to Warrick et al generally follows the concept of U.S. Pat. No. 3,467,450, but employs a more elaborate process. In this case, an adaptor is used consisting of a bore 225 and a shaft 228 eccentric as to each other. As the table saw height and angle change, the motor mount rotates the eccentric adaptor through a torsion spring so as to maintain a constant belt tension on the jointer side of the machine. As in the case of U.S. Pat. No. 3,467,450, the eccentric is constant, resulting in a tension adjustment of the system as the adaptor is rotated. But this adaptor could not track a belt because the eccentricity is constant and would only adjust the tension in a two pulley system.
U.S. Pat. No. 1,171,347 to Morse teaches an adjustable bearing and coupling for a pulley. An eccentric bearing member 8 has a constant eccentricity through its width. The eccentric is not skewed so that it will not track a belt, unlike the individually steerable pulley of this invention.
U.S. Pat. No. 240,898 to Fairfield teaches a flywheel and bearing for a sewing machine stand. It takes up for bearing wear by the use of a conical washer which is adjustable via a bolt and set-nut. It has no application for a system for tracking a belt.
As such, it may be appreciated that there is and continues to be a need for a new and improved independently steerable idler pulley as set forth by the instant invention which addresses a) the effect which a belt's camber, or lack of edge straightness, has on the dynamic alignment of the belt to the pulley during operation, 2) any parallelism misalignment between the drive and idler shafts, and c) one dimensional eccentricity of the pulley outer diameter to the pulley bore.
Accordingly, there is a need for a new and improved system as set forth by the present invention which addresses both the problems of ease of use as well as effectiveness of structure and, in this respect, the present invention substantially fulfills this need.